System of control



R. E. HELLMUND. SYSTEM OF CONTROL.

APPLICATION FILED MAY 7, I919. 1,417,733.. Patented May 30, 1922.

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4' around? 74a Gmuna WITNESSES: iNVENTQR fiua o/f Efi'eMWe/M BY Z ATTORNEY E. HELLMUND. SYSTEM OF CONTROL.

4 I APPLICATION FILED MAY 7| I919- 1,417,733. v Patented May 30, 1922.

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Ground WITNESSES: Y I I INVENTORY Rudolf He/lmqnd.

ATTORNEY R. E. HELLMUND. SYSTEM OF CONTROL.

I APPLICATION FILED, MAY 7. 1919- 1,417,733. Pat nted May 30', 1922.

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I BY 3 v ,Arionnsv HELLML-ND.

SrbT M OF CONTROL. -APPLlC .'HON M20 MAY 7. ran

Patented M11330, 1922.

INVENTOR Rudo/fff/d/m ufld.

ATTORNEY R. E. HELLMUND.

SYSTEM OF CONTROL. APPLICATION FILED MAYI. 1919.

1,4: 1 7,733 Patented May 30, 1922.

5 SHEETS-SHEET 5.

m WITNESSES: INVENTOR ATTORNEY m for dynamo-electric machines and RUDOLF E'HELLMUND, O1 SWIBSVALE,

PENNSYLVANIA," ,assmnon r0 wnsrmo- HOUSE I'II'IJC'IIJRIC 0i MANUI'A'CTURINGflOMPANY, A COBPQELTION' Q! PENNSYL- VANIA.

To all itvmayconcem: I

Be it known that RUDoLr HnnmrUNn, a citizen of the United States, and aresident I of Swissvale, in the county of Allegheny and 6 State of Pennsylvania, have invented a new and useful Improvement in Systemsof Control, of which the following is a fication. a

My invention relates to systems of control artlcularly to certain automatic control eatures' foraccelerating and regenerative 0 ation of electric railway motors and the li e. i The object of my invention, in general, is to provide a more reliable and advantageous system of regenerative control in various aspects than has been proposed heretofore. Specifically considered, one object of the invention is to provide, in conjunction with 2 an automatic control system, a motor-type relay device havin a time-element of operation smaller than t at of themain machine, whereby undesirable over-regulation of certain motor circuits is reliably-prevented. Another specific object of my invention is to provide a novel auxiliary control system for eifectin automatic transition of a lurality of e? series relation, or Vice versa.

' 80 Other minor" objects and advantages of the present invention will become evident from the following detailed description, taken in con'unction with the accompanying drawings, w erein-- Figure 1 to Fig. 7, inclusive, are simplified diagrammatic views of various modifications embodying the principles of my present invention. 1

Fig. 8 is a diagrammatic view of the com 4 plete main circuits of the preferred form d of the invention.

Fig. 9 is adiagrammatic. view of the auxiliary control circuitsfor governing the various switching devices that are shown in Figs. 10 to 15, inclusive, aresimplified diagrammatic views illustrating one feature of my invention. Y

In connection with the automatic control 6 of direct-current railway motors, and the like. during the regenerative period, difficulty has been experienced in obtaining precise control of the system by reason of the fact that, with the customarily employed 56 separately-excited main machines, the field sys'rmm or common.

of, including the motor ectric motors from paralle to Specification Letterlra'tent. Patent d May 30, 1922. Application nled May .1, 1919. Serial in. 205,2 5.

windin s res 0nd ve slu ishl to current regulatIon, sihce the rha E o cii cuits there,

rame, are composed of solid magnetizable material, in which eddy currents are created. Consequentl the current relay or limit switch that is ord1- narily utilized for governing the automatic control of the system does not movequickly enough to prevent the regulating a paratus from taking several steps or note es at a time instea of the desired single ste It has prev1ously been suggested as a remedy for this condition, to connect the armature of a motor-type relay that governs the circuit regulation across an im- 7 pedance or inductive device that is traversed by the ;ma1n-mach1ne current. However, this suggestion has not proved eflicacious in all instances and, in the'p'resent invention,

therefore, the relay action is temporarily 7 5 influenced during the active control operation by changes in the field excitationof the mainmachine or of the exciter so that the initial change of circuit conditions affects the relay inadvance proportionately to the final 30 current condition that corresponds to such change.

Another difliculty encounteredin revious regenerative-control equipments re ates tothe connection of themachines to the Supply. circuit, after a coasting or free-running period, by balancing the machine voltage against the line voltage. In many instances,

"such regulation resulted in a period of practically zero line current after closing the switch that connects the machine to the su ply circuit, since a certain time element is required to actuate the control apparatus. that regulates the voltage of the momentumriven machine. In .order instances, the above-mentioned slu gishnes of the field winding caused .fiel -excitation changes in the wrong direction after the line switch was closed, whereby motoring current was first obtained when regenerative current was intended, or vice versa. Evidently, such con ditions materially increase the time element between the'initial movement of the master controller and obtaining thedesired operating result. The present invention is, therefore, also intended to obviate the difiiculties just recited.

Still anotherv difliculty was experienced with some of the prior regenerative-control systems by reason of the fact that the speedsponding to regeneration, the last series curve is located considerably below the first parallel curve during motoring operation, thereby'necessitating that the motors run with resistance inserted in circuit for an undue length of time, entailing excessive the desired re losses. To avoid the two undesirable conditions mentioned, the last series curve should be approximately parallel to the first multile curve, at least for motoring operation. lhis result may be accomplished either by flattening the last series curve, steepening the first parallel curve or by doing both. The present invention is adapted to effect lation and thus eliminate the correspondlng troubles in the prior art.

Referring toFig. 1 of the drawings, the

, system shown comprises suitable supplycircuit conductors Trolley and Ground; a main dynamo-electric inachine 18 having a commutator-type armature 20 and a field winding 22 of the heavy-coil series type a balancing or stabilizing resistor 24; 'an auxiliary generator or exciter 55 for the main field winding, a torque-motor-relay device 40 for regulating the voltage of the momentum-driven main machine, in this case, by varying the active circuit value of the stabilizing resistor 24; an impedance or inductive device 140 that is traversed by the main-machine. current and is connected to the torque-motor relay device 40 in a manner to be set forth; and a plurality of auxilT iary-circuit translatin devices, namely, a resistor 144 and an inductive device 143 that are alternatively connected in circuit by a switch 145, under conditions to be set forth. 4

The torque-motor-relay device 40 comprises a commutator-type armature 41 that is connected across the main-circuit inductive device 140; an exciting field winding 42 that is connected through either the resistor 144 or the inductive device 143 to the terminals of the main field winding 22; and a damping field winding 141 which may be connected in circuit by closing a switch 142, during the motoring period, to produce a relatively large time element of operation. Upon the operating shaft 48 of the torque-relay armature 41, a small drum or cylinder 49 is mounted and carries any desired number and arrangement of contact segments for co-operati-ng with a plurality of control fingers to thus regulate certain auxiliary control circuits in accordance with the osition or deflection of the relay device. In t e resent instance, the relay is preferably a apted to govern the'action of the controller 146, as fully illustrated and described in connection with Fig. 8, whereby the desired precise regulation of the mainmachine circuit is automatically effected through the agency of the illustrated torquemotor relay.

The main-armature or load circuit during the regenerative period is indicated by the solid arrows and may be traced from the supply conductor Ground through the stabilizing resistor 24, main armature 20, in ductive device 140 and thence to the other supply conductor Trolley. The main field winding or exciting circuit is indicated by 'the dotted arrows and is established from the positive terminal of the exciter armature 55, through the stabilizing resistor 24 in the same direction as that taken by the load current, and thence, through the exciting field winding 22, to the negative teriliary' circuits may be employed with any.

suitable ty e of main regenerative circuits and, there ore, further detailed description of such main circuits is not deemed to be necessary here.

The resistor 144 is connected in circuit with the relay field winding 42 during regenerative operation. This resistor, to ether with the small damping constant of t e relay field winding, imparts thereto a much smaller time-constant than that of the main field winding. Assuming that a control step is being taken during regenerative control, by actuating. the controller 146 to short-circuit a portion of the stabilizing resistor 24, an increased main field strength and, consequently, increased regenerative current will be obtained. However, certain delays will be caused in such changes by reason of the damping and self-inductive effects of the various circuit elements, articularly of the -main field winding 22. 6n the other hand, an increase in the main field current will produce a correspondingly augmented transient field voltage which will be impressed upon the field-winding circuit of the rela device. Since the relay circuit has a sma l time-constant, the change in its flux is produced at once, whereby the armature of the relay device is deflected to prevent more than one control step from being taken.

If the torque relay 40 is employed during acceleration also, the previously described actions may not pr uce proper results.

Assuming, for instance, that the main mos tor is being accelerated by weakenin the field strength through the agency of the controller 146, a transient low field. voltage willbe obtained. Since the time-element of the relay field circuit is small, under the conditions previousl described, this low voltage will reduce tlie lay, which prevents it from being deflected quickly enough and'thus permits an additional step of the controller 146 before stable excitation conditions inthe main machine are attained. Consequently, under accelerating conditions, it is desirable to pro vide the relay field circuit with a time-element that is slower than that of the main- Inachine field winding. For this purpose, the inductive device 143 is employed during acceleration instead of the resistor 144, as indicated by the dotted-line position of the switch 145, and, also, [the damping field winding 141 is utilized, as likewise indicated by the dotted-line position of the switch 142. Such circuit connections will, therefore, pro vide thedesired results during acceleration.

By employing the different sets of connections that are shown in Fig. 1, therefore, the torque-relay device 40 may be effectively and desirably employed during both the regenerative and the accelerating periods of the main machine. As previously mentioned, the provision of the main-circuit impedance 140 makes for rapid response of the relay to changes in'circuit conditions.

Referring to Fig.2, the main machine, the exciter and the stabilizing resistorv are employed. as already described in connection with Fig. 1,. while the torque motor 40 is provided with the single exciting field winding 42 and, therefore, is primarily adapted for use during regenerative control. A small transformer 33 has its primary wind ing 35 connected in series relation with the main field winding 22, while the secondary winding 34-of the transformer is connected in series relation with the armature 41 of the relay across the main-circuit inductive device 140. A variable resistor 147 is connected in series relation with the relay exciting field winding 42 across the circuit comprising the main field winding 22 and the primary transformer winding 35.

The system under consideration, insteadof effecting only the relay field circuit by the changes taking place in the main field winding, influences the relay armature circuit as well. The resistor 147 serves the same purpose as the resistor 144 of Fig. 1, while the small transformer 33 accomplishes the desired additional purpose. Whenever a portion of the stabilizing resistor 24 is shortcircuited by the controller 146,.a certain increased current will flow through the prifield strength of the remary transformer winding 35 which, in turn, increases the total flux offlthe transformer. Such action induces a voltage in v the secondary transformer winding 34 that is adapted to increase the current traversing the relay armature 41, thus bringing about the deflection thereof somewhat previous to the increasepofregenerative current to prevent the control apparatus from taking more than the desired single operating step.

Referring to Fig. 3, the same result is ac-' complished by connecting a separate field coil 148, constituting a portion of the excitingfield winding, in series relation with the armature 41 of the torque relay device 40. This additional field C011 is substituted for the small transformer 33 of Fig. 2. The operation of the system may be briefly set forthas follows:

Upon an increase in the current traversing the main exciting field coil22, by reason of a short-circuit of a portion of the stabilizing resistor 24, an increased voltage is induced in the additional field coil 148, whereby an increased current flows through the relay armature 41 previously to the actual change in the main-armature current, and thus the controller 146 is prevented from moving more than one notch.

In Fig. 4, the desired regulation'is 0b- 95 tained by, connecting the primary winding 35 of the transformer 33 in series relation with the exciting field winding 42 for the relay device. The secondary transformer winding 34 is again connected in circuit 100 with the relay armature 41. as in Fig. 2. Furthermore. the resistor 144 and the inductive device 143 are again utilized during the regenerative and the accelerating periods, as previously described in connection with 105 Fig. 1. Preferably the damping field winding 141 for the. relay device 40 isalso employed in the system that is shown in Fig. 4 for the same purpose as that set forth in connection with Fig. 1.

By connecting the transformer 33 in the manner shown in Fig. 4, the current traversing the relay armature 41 in all cases causes the relay device to be actuated in the proper direction. Assuming regenerative 115 operation. for example, and that a control step is being taken, producing an increase in field voltage. then such increase raises the current value in the primary transformer winding 35 and the voltage of the 120 relay armature 41 whenever regenerative current is flowing through the inductive device 140. While accelerating and taking a control step that gives decreased field voltage, the electromotive force induced in the 1 secondary transformer winding 34 will be in the. opposite direction. However, the acopposite direction, so that the voltage induced in the secondary transformer winding 34 again efi'ects the desired movement of the relay device, the deflection thereof being in the reverse direction from that taken during regenerative operation. Whenever the control system is arranged to manipulate the excitation of a field winding of the exciter machine, additional time: elements or delays are necessarily introduced between the actual taking of a control step and the resultant changes in the mainfield-ivinding and armature currents. In such cases, therefore, it is desirable to influence the action of the relay device directly by the changes that take place in the exciter field current. In Fig. 5, the desired result is accomplished by an additional field winding 58 for the exciter 55, such-wind ng being connected in series relation w th the relay-device field winding 42 acrossthe main exciting field winding 22. T o obtain proper functioning of the exciter during both regeneration and motoring, a reversing switch 150 for the additional field winding 58 is provided. However, if the field winding 58 is connected in series relation with the relay armature 41, the reversing switch 150 may be omitted.

In the present system, a resistor 60' is connected across the chief exciting field winding 57 for the exciter 55 and a controller 149 is governed by the torque relay device 40, to regulate the active circuit value of the resistor 60, thus, in turn, varying the exciter voltage and the main-armature voltage. Furthermore, an auxiliary driving motor 54 for the exciter machine is provided with an exciting field winding 56, which is connected in series relation with the armature 54 and the field winding 57 for the exciter across the supply-circuit conductors.

Fig. 6 discloses an arrangement permitting the use of an auto-transformer 151 in place of the two-coil transformer 33 that was shown in previous figures. The autotransformer winding is connected in series relation with the exciting field winding 42 for the torque relay device and the resistor 147 across the terminals of the main exciting field winding 22, while the relay armature 41 is connected across the main-circuit inductive device 140 through a variable portion of the auto-transformer winding 151. The resistor or inductive device 147 and a resistor 152, which is connected across the exciting field winding 42 for the relay device, are adjusted to produce the proper amount of damping and self-inductive effects inthe relay field circuit. It is assumed, in the present instance, that the timeelement'of that circuit is either the same as, or slower than, that of the main field winding, and that the voltage added in the relay armature circuit by the auto-transformer winding 151 is inherently adapted to deflect the relay device in the proper direction after the initiation of a control step, whereby further undesired control operations are prevented.

In Fig. 7, a field winding 58a is provided for the exciter armature 55, in addition to the field winding 57, and is connectedin series relation with the main armature 20. In other words, the field winding 58a is energized in accordance with the load or regenerative current of the system. The relay armature 41 is connected, through a variable resistor 155 and a ermanent resistor 154, across the load-excited field winding 580., while the relay exciting field windin 42 is connected in direct parallel relation with the exciting field winding 22. During stable oper ating conditions, the ohmic drop across the field winding 58a, increased, if necessary, by the use of the series-connected resistor 154, supplies the normal voltage to the relay armature 41 and maintains the relay device in its intermediate normal position. Whenever the current traversing the exciter field winding 58a changes, however, a corresponding transient or inductive voltage is added to the above-mentioned ohmic drop. Consequently, the current flowing through the relay armature 41 is varied in such manner as to produce the desired deflection of the relay device and thus prevent undesirable control operation, viz, the movement of the controller 149 through more than one step at a time.

If a plurality of main motors an employed and series-parallel operation thereof is desired, the illustrated resistor 155 may be introduced into the relay armature circuit during parallel motor operation, to compensate for the increased current in the load-excited field winding 58a for the exciter machine, whereby the same values of current and voltage are supplied to the relay armature itself.

Referring to Fig. 8, the system shown comprises the sup ly-circuit conductors, Trolley and Groun a plurality of main dynamo-electric machines 18 and 19, respectively having armatures 20 and 21 and field windings 22 and' 28; a plurality of stabilizing resistors 24 and 25 and of accelerating resistors 26 and 27 for the respective machines; an auxiliary motor-generator set 53, or the like, for supplying energy to the .main field windings; a torque-motor-relay device 30, the transformer 33, and the main-circuit inductive device 140, as previously described; the torque motor relay device 40 which, as hereinbefore mentioned, is employed for the purpose of efl'ecting automatic'control of the system after the line switches are closed, the relay device 40 acting in conjunction with an auxiliary transformer 43 that is energized in accordance with the driving-motor current of the motor-generator set 53. For further pur- .poses of control, a plurality of switches, 1 to 17 inclusive, are connected in various circuits to be described, and a plurality of solenoid-type relay devices 50, 51 and 52, are also utilized for certain automatic control oper ations. i

As described in detail in connection with Fig. 9, the torque-motor relay device 30 governs the main machine voltage before the line switches are closed, that is to say, during the coasting operation of the vehicle. Under stable conditions, while the line switch 1 is open, the relay device willproduce no torque when the line and the machine voltages are balanced or approxi- -mately equal, since the relay armature 31 is connected, throughthe' resistor36, across the line switch 'l. However, whenthe two voltages differ by a predeterminedamount, torqueinthe one or theother direction will be produced. in the relay device 30,"causingit to rotate-to some one'of the-four operative positions thereof. As will be appreciated rom the' foregoing des'criptiom; it is desirable to'. anticipate" voltage changes "in the system, particularly with respect to the closing of switch 1, in orderv to reduce the time rial No. 190

needed for effecting regenerative operation, for example, after the operator has moved his master' c0ntroller tothe corresponding position; j y a The present arrangement .ofthe relay device 30 and the transformer-33 is adapted to require a relatively small transformer ca pacity. In In co pending application, .Se-

335, filed September ,7, ,1917. patented Dec. 14, 1920,: No. 1,361,994, 'a simi-' lar voltage-balancingrelay is shown in combination with a transformer, which, how ever, must be of relatively large capacity, since a comparatively high voltage must be induced therein to accomplish the desired" effects. In the above-identified application, the secondary winding of the transformer is connected in series relation with the relay armature 31, whereas, in the present instance, the secondary transformer winding is connected in parallel relation to that armature. The arrangement of trans former coils is such that the transformer core is magnetized in the same direction by both of them, whereby, if the'main machine voltage is rising, causing an increasein 'currentto traverse the resistor 37 and the primary winding 35 of the transformer 33,

such action willinduce avoltage in the sec: ondary transformer winding 34 that assists the normal flow of current therein. Consequently, the major portion ,of the current traversing the resistor 36 is caused to traverse the secondary transformer winding 34, and only a small fraction of that current passes through the relay armature 31.

Since the opera-ting voltage of the relay. 9

armature, as well as the current, is alwa s of a relatively low value, it fOllJOWS that t e voltage and current of the transformer,

and, therefore, the capacity thereof, may be relatively small also.

The relay armature 31 is mechanically connected, by a shaft 38 or otherwise, to a small drum or cylinder 39 which is normally maintained in the illustrated position by means of a plurality of centering "springs 79. The purpose of the various contact segments shownwill be set forth later in connection with Fig. 9.

' The torque-motor limit relay 40 comprises a commutator type armature41 that is connected through a secondary winding 45 of the transformer 43 across the main-circuit inductive device 140, while an exciting field winding 42 for the relay hasone terminal connected to a point intermediate equal sections 46 and '47 of another secondarywindthe present instance,- this resultis accomplished by connecting one terminal of the field winding 42 to a point intermediate the transformer sections 46 and 47, the outer ter minals of which are connected to suitable control fingers that engage a contact segment 49 of the relay 40 in its deflected positions A and B, respectively corresponding to acceleration and regeneration. Consequently, only one of the transformer sections 46 and 47 is actively employed at any time, and the desired reversal of current through the exciting field winding 42 of the relay device is automatically secured in this manner. v

The relay device 50 is connected in parallel relation to the main exciting field winding 22', and is employed forthe'pu'rpose of holding the line switch1jopen-until stable conditions, are established, when .is desired to connect the machines to the supply circuitjx- Whenever. the excitation of the main exciting fieldwi'nding 22 is fluctuating, the effective voltage thereof will be i sufficient .to maintain the relay'device'50- in its upper or open-circuitlp'ositlon, as further described in connection; with Fig. 9.; g

The. relay device 51 hasit's actuating coil connected in series relation with the main armature 20 and acts in conjunction with the relay device 40 for the purpose of automatically controlling the operation of the system. Preferably, the solenoid-type current rela 51 is arranged to be active only during tlle high-speed or parallel connection of the main machines, and it is adapted to prevent operation of the main regulating controller, or the like, whenever the current traversing the main armature 20 exceeds a predetermined value, as subsequently set'forth in greater detail. a

The relay device 52 measures the voltage of' the main machine 18, being connected from the left-hand side. of the switch 1 through the exciting field winding 32 forthe torque relay 30 to the negative supply-circuit conductor, Ground. The relay evice 52 is adapted to govern certain circuits,'to be described later, underlow-voltage conditions of the sup ly circuit.

Referring to ig. 9, the auxiliary system shown comprises a master controller having a plurality of operative positions, A, H-

and D, respectively, standing for accelerating, holding, and decelerating; and a sequence drum 71 having a plurality of op erative positions a to 2, inclusive, beingdriven by a pilot motor 7 2', or the equivalent The actuating coils for the switches -1 to 14 are designated as 1 to 1 1, and-the .corresponding control fingers for the sequence drum 71 are marked 1, to 1 1,. In addition to the various contact members of the torque relay devices 30 and 40, together with the. contact disks of the solenoid type relay devices previously mentioned, a lurality of electrical interlocks, of the familiar type shown in connection with the" switch 1 in Fig. 8, are-employed, energy for the auxiliary controlling circuits being driven from a, battery 78, 017.-

the like. v

The pilot motor 7 2-comprisesa commutator-type armature 73 that is directly connected to the operating shaft of the sequence drum 71, and an exciting field winding having two parts, 74: and 75', which are alter 'natively energized to produce movement ofthe armature 73 and of the sequence drum 71 in the one or the other direction. I Whenever the field coil 7 5 is energized, the drum moves forwardly, that is, from the illustrated ofl? position marked fo towards the final operative position 2, whereas, the

'energiz'at io'n of the other field coil 74 effects a backward movement of the sequence drum. Assuming that it is desired to effect acceleration of the illustrated main machines from rest, the master controller 7 O is actuated to itsposition A, thereby first interrupting a circuit from'the positive terminal'of the battery 78 through conductors 160 and 161,

control fingers 76, which are bridged by contact segment '77 of the master controller,

-conductor 162 and actuating coil 1710f the switch '17" to the negative terminal of the battery. Consequently, the switch 17 is closed whenever the master controller oc- ,cupies its 011' position, to weaken the field ing 57 of the exciter, which is thus prepared for supplying the necessary exciting voltage to the main field windings 22 and 23.

As soon as the master controller reaches its position A, another circuit is established from the positive terminal of the battery 78 I through conductor 163, control fingers 8 1 which are bridged by contact segment o the relay device 40 in its normal intermediate position-,whence circuit is continued through the contact disk 164; of the current relay 51 in its'lower position, "conductor 165,

control fingers 82 and 81, which are'bridged by contact segment 83 of the master controller, conductor 166, control fingers 97, which are bridged by contact segment 98 of the relay device 30 in its normal intermediate position, conductor 167, 'field coil 75 of the pilot/motor 72, conductor 168 and armature 73 to the negative battery terminal. Consequently, the sequence drum 71. is actuated to its-initial operative position a.

Upon such movement of the sequence ,drum 71, a further circuit: is established from the positively energized conductor 163 through conductor 170, the actuating coils 2', 3' and 14 and corresponding control fingers 2,, 3, and 14,, whence common circuit is continued through contact segment 87 of the -sequence drum, control finger 86 and conductor 171, to the negative battery terminal. Switches 2, 3 and 14 are thus closed directly by the sequence drum.

Switch 1..may also be closed at this time by means of a circuit including conductors 163 and .172, control fingers 89, which are bridged by contact segment 88 of the sequence drum, conductors 173 and 17 1, control finger 90, contact segments 91-and 92 and control finger 93 of the relay device 30 (which now occupies its extreme. position L after the switches-2 and 3 areclosed, when the voltage supplied tothe relay device armature 31 is relatively high because of the initial low or substantially zero voltage of the main machines), circuit being continued .from thecontrol fingers 93 of the relay device 30 through conductor 175, contact disk 176 of the relay 50',provided that this relay occupies its lower position corresponding to stable main field-excitation conditions, circuit being completed throughthe actuating coil 1',controlfinger 1,, to the contact segf ment 87 of the sequence drum, and thence to the negative battery terminal, as previously described. n

. ment 104-of the master controller, whence I Y 105 and conductor 160 to the terminal. In'this way, the ine switch 1 is circuit iscontinued through control finger sitive'battery held closed,j irrespectlve of the subsequent nioveme'nt of the excitation relay 50 or of theooasting torque relay 30. vFurthermore 1 an interlock l-inbridges conductors. 166 and 167 to further renderithe operation of 'the' sequence drum '71 independent of the contact se ent 98 of the relaydeviceBO'.

v fi lievlast-mentioned interlock permits further forward movement of the sequence -,drum, which is held in position a until fieldexcitation conditions are stable and 'the switch 1 has closed to causethe drum 39' to return from position L, wherein the pilotmotor circuit is interrupted at. control fini gers 97 to the centralposition, ofi',

Further step-by-step movement of the se- 2, conductor 187, main field winding 23, stablizing resistors 25 and 24, main field winding 22 and conductors 183 and 184 to s I the opposite terminal of the exciter armature.v

An auxiliary circuit is established from the trolley through conductors 180, 190 and --191,. driving or motor armature 54 for the ,exciter armature 55 and field winding 56 for the driving armature tojunction-point 192,

where the circuit divides, one, branch including field winding 57 and a second junction-point 193, the other. branch traversing variable resistors 60, 61 and 62 and primary winding of the transformer 43 to the junction-point 193, whence a. common circuit is continued toground'.

-Referring again to Fig. 9, it will be observed that movement of the se uence drum 71 through positions I; to 9, inc usive, energizes the actuating coils S, 11", 9', 12', 10"

and 13 through suitable interlocksin that 'order,to'gradually short-circuit the acceler- 1 ating resistors 26 and 27 and accelerate the motors to series relation. 7

In vpositions h z'a-ndl-j, of the sequence 11191166 drum 71 is d p n t P the t rque the j exoiter armature, and 7 thereby correrelay device 40, which interrupts the previ-- ously traced circuit of the pilot motor. 72 whenever the'torque of the main machine differs froma p'edetermined value. The relay device 40 alone governs the action of' the pilot motor throughpositions a to w inclusive of the sequence drum, while the solenoid-type current relay 51 is inoperative to govern the pilot motor during the positions mentioned, since the contact members i of the relay 51 are bridged by control fingers 95 and contact segment 94 of the sequence drum. However, in thehigh-speed parallel positions y'and .2 of the sequence dr ii'n, the current relay 51 is made effective for the purpose of preventing Y undesn a ly high ratios of armature ampere-turns to fieldwinding ampere-turns, which ratios are riod of weak field-excitation accompany ng f high-speed operation of the main machine.

'Turnin'g'temporarily to Fig. 8', the main circuits that are formed by the closure of switches,1,2, 3 and 14 maybe'traced'as fol lowsz; from the trolley through conductors 180 and '182, the inductive device 140, switch .1, the entire accelerating resistor 26, the

main armature 20-, actuating coilof the cur rent relay 51, the stabliz'ing resistors 24 and 25, main armature 21-, the entire accelerat ing resistor 27, and switches 3 and 14 to the negative conductor Ground. Another circuit, is established from the positive terminal of the exciter armature 55 throu-ghiconductors 185 and 186, switch tion, as well known, serves to further increase the operating speed of the main,

motors.

for the exciter armature 55 is rendered ac tive by reason of the de-energization-of the reduce the excitation of .the'

a drum, portions of the resistor60 are short circuited to weaken the-field winding 57 for In position is, the other field windingts 10o,

actuating coil 14 and the consequent opening'cof the switch 14, which normally shortcircuits the field winding 58. The two field windings 57 and 58 are differentially disposed duringacceleration of the main machines for, the purpose of flattening. the last series characteristic curve thereof, as previously explained in detail. K

1 ,In position Z, the actuatin'gcoil 101 is "do energized to re-in'sert a portion of the ac-] I celerating resistor 26 in the motor circuit, as an initial transition-step. See Fig." 10.--

'In' position m, the actuating coil '4 is en'- ergized, thereby closing the switch 4 and impressing the full exciter voltage across the main field win'dings22 and 23 in parallel .relation, the stabilizing resistors 24 and 25 being still connected in respective series relation with the field windings. The closure of the switch causes the main'arm'ature 20 to absorb the major portion ofthe f operatingvoltage, while the other mainarmature 21 is energized to 'arelatively slight I 7 degree, since the load current forthemost only, a relatively small portion thereof pames through the field winding 23, which part traverses the stabilizing resistor 25- and lel connection of is connected in a local shunting circuit including switches 2 and 4 and the resistor 25. See Fig. 11.-

During the transitional movement through positions I and m, a portion of the resistor 60 is again inserted in circuit to corres 0ndingly strengthen the field winding 5 for the exciter armature 55, while the differential field winding 58 is again short-circuited in position m by the closure of the switch 14. In this way, the exciter voltage is increased in preparation for the initial paralthe main motors. See F i 11.

n position 11., switches 11, 12 and 13 are opened to reintroduce. the resistor 27 in circuit with the main armature 21. See

Fig. 12.

In position p, the switch 5 is closed, whereby the main motor 19 is included in a local or shunting circuit that comprises the armature 21, stabilizing resistor 25, switches 4 and 5, ground, switches 14 and'3, and resistor 27. Thefield winding 23 is also shunted by a circuit comprising stabilizing resistor 25 and switches 4 and 2, as mentioned above.-

At the same time, a portion of the resistor. 60

is short-circuited to slightly reduce the excitation of the'field winding 57 for the exciter armature the value of such excitation being the maximum that is employed duringthe greater portion of parallel Ina-- chineoperation. See Fig. 13.

. In position g, switches 2 and 3 are opened,

while in position 1' switch 6 is closed, thereby establishing parallel connections for the .main fieldwindings. See Fig. 14. r Inposition s, the switch7 is also closed,"

which completes'the parallel connection of the main armatures. See Fig. 15.

. One novel feature ofthe transition just described isthe annulment of the excitation of the shunted machine, in spite of the separate excitation thereof, thus affording the advantages of the well-known shunting transition of straight series motors. With prior systems embodying separate excitation,-

the residual field magnetism has set upundesirable currents in the shunted armature.

Referring temporarily to Fig. 8, the para allel connections-just recited may be traced as follows: from the trolley through conduc-' tors 180 and 182, inductive device 140', switch 1, a portion of the accelerating resistor 26, main armature 20, actuating coili of the current relay 51, stabilizing resistorv 24, and switches4 and 51-to ground; The

circuit for the other main armature is vcontinned 'from conductor 180 through conduc tor 190, switch ,7, the entire accelerating re'--' sistor 27 ,main armature 21 and stabilizin resistor 25 to theswitches 4 and 5. In positions t to w, inclusive, of the sequence drum, the remaining resistor shortcircuiting switches 10 to 13, inclusive, are

position H as soon as the sequence-drum occupies the desired position. Such action completely de-energizesfthe pilot motor 72, by reasonof the disengagement of the contact segment 83 from control fingers-81 and 82 Assuming that regenerative operation is desired after. the main machines have attained their full-speed relation, or any other suitable stage, the master controller may be .moved to its position D, whereby a circuit is established from the positive terminal of the battery 78 through conductor 1633, contact members 84 and 85 of the torque limit relay 40 in its normal intermediate position, the contact disk 164 of the solenoid-type limit switch 51, conductor 165', control fin xfi gers 82 and 101, which are bridged by contact segment 102 of .the master controller in position D, conductor 200, contact members 99 and 100 of the relay device 30, conductor 201, field coil 74 of the pilot motor, and thence through conductor168 and armature 73 to the negative battery terminal. Consequently, the sequence drum. 71 is moved ,backw'ardly through its successive positions under the control of the torque limit relay 40, and also-the current relay 51 1n pos1- tions 2 and y, in accordance with previously described principles.

. Whenever coasting operation is desired, the master controlleris movedto its ofi' position, whereby the circuit of theactuating coil for switch .1 is opened directly and switches 7*to 13, inclusive, are likewise opened by reason of the exclusion of the various illustrated interlocks from the .cir-

icuits of the respective actuating coils.

The chief function of the relay device 30 is the automatic regulation of the system at the termination of a period of coasting, as previously mentioned, For example, if acceleration of the main motors is desired after coasting period, the master controller 118' again moved to its position A. The relay drum 39'then assumes some position that is dependent'u onthe vehicle speed and also .upon the pOSltiOIl thatthesequence drum 71 occupies at the time. I x If the relay-drum 39 moves to its position "L- whilethe se uence drum 71 is in its position'o or 0;, t e previously described acceleratmg operation 1s efl'ected. However,

if the'drum 71 occupies any other position,

the contact members 88 and 89 thereof are inefi'ectiv'e to complete the circuit of the line switch 1. Under such'conditions, a circuit is established from the positively energized conductor 160 through conductor 202, control fingers 112 and 110, which are bridged by contact segment 111' of the master controller, conductor 203, interlock l-out, conductor 204, control fingers 108, which are bridged by contact segment 109 of the sequence drum, conductor 205, control fingers 106, which are, bridged by contact segment 107 of the relay 201, and thence, through the field coil 74 and the armature 73 of the pilot motor, to the negative battery terminal. Consequently, the sequence drum 71 is moved backwardly until either the relay drum 39 moves out of 1 its position L or until the sequence drum 71 has returned to its position a. In the latter case, the circuit of the pilot motor, as just traced, is broken by the disenga ement of contact segment 109 fromcontrol ngers- 108 of the sequence drum, whereupon the switch 1 is closed, as initially described above.

If the relay drum 39 occupies its position M, the line switch 1 is clbsed, provided the excitation relay 50 occupies its lower position corresponding to stable. conditions,

through a circuit that is established -from 7 its positions conductor 160 through conductor 207 control fingers 105- and 115, which are bridged by contact-segment 104 of the master controller, conductor 208, control fingers 114 and 93, whichare bridged by contact segment 92 of the relay drum 39 in its position M, and thence through conductor 175, the contact disk 176 of the excitation relay 50 and the actuating coil 1 of the switch 1, as

v previouslytraced. 40

If the rela drum 39 occupies any one of G, or 011', the line switch 1 cannot be closed, b reason of the interruption of its actuating-coil circuit, but a new circuit is established from thepositively energized conductor 163 through contact members 84 and 85.0f the torque limlt relay '40 and contact disk 164' of the current relay 51,'whence circuit is continued through 'conductor165, control fingers 82 and 81,"which are bridged by contact .segment 83 of the master controller, conductor 166, "contact members 97 and 98 of the relay drum 39, in any one of the positions .ofl', G, or H of the drum, conductor 167 and field coil-7 5 of the pilot motor. Consequently,the se uence drum 71 ismoved in a forward direction toreduce the main machine voltage until, the

relay drum 39 moves to its position M, vwhen the line switch 1 may be closed, as previously described.

Assuming that regenerative operation'gis desired after a coasting period, the master controller is actuated to its position D. Again the relay 39 may then occupy any one of its five positions.

-'drum 39 in its position L, conductors 206 and wherein the line switch If the relay is actuated to its position H the line switch 1 cannot be closed, but a new circuit is established from conductor 160 through conductor 202, control fingers 112 and 118, which are bridged by contact segment 111 of the master controller, conductor 210, interlock l-out, control fingers 116, which are bridged by contact-segment 117 of the relay drum in its osition H, and conductor 211 to the con uctor 166, when circuit is completedthrough the ilot motor field coil 75, as reviously trace The seguence drum 71' 1S thus moved in a forward irection until the main-machine voltage is low enough to cause the tor ue relay 30 to assume its positionG. Un er such conditions, the line switch 1 may be closed through a circuit including conductors 160 and 207, control fingers 105 and 120,- which are bridged b contact-segment 104 of the master contro ler, conductor 215, control fingers 119 and 93 of the relay drum 39 in its positionG, whence circuit is completed through the conductor 175 and the actuating coil- 1' of the switch 1, as hereinbefore described.

If the relay drum 39 occupies any one of its positions ofi', M or L, the line switch 1 cannot be closed, but a circuit is established through contact members 85' and 84 of the'vtorque limit relay 40, contact members 82, 101, and 102 of the master controller, and contact members 99 and 100 of the relay drum 39, in accordance with the previously traced circuit, to the field coil 74 for. the

pilot motor, whereby the sequence drum71 is moved backwardly until the main machine voltage is increased sufiiciently to cause the torque relay 30 to assume its position G, 1 may be closed, as

previously described.

It should befurther'noted that at any time when the torquerelay 3O occupies'its position L, that is, whenever the main machine voltage is relativelylow, the switch 15 is raised to its upper or circuit-opening positionby means of a circuit including conductor 160, actuating coil 15 of the switch 15, conductor 220,, control fingers 221 and.

222, which are bridged by contactsegment 223, and thence, through conductor 224, to

the negative battery terminal.

In this way, the switch 15 is opened to insert the. resistor 62, inthe circuit shunting :the excitingfield winding 57 for the generk ator armature 55," thereby quickly increasingthe main-machine voltage. q Onthe' other hand, when .the main-machine 'voltage is relatively high during the coasting period, the-relay device 52 will be lifted to its circuit '-closing position to com-1 plete acircuit including the actuating coil 17 of the switch 17 and the contact members of the relay 52. By thus shunting the exciting field winding 57 for the exciter with the resistor 63, which has relatively low resisting through the resistor and the primary ance value, the excitation of the generator armature 55, and, therefore, of the mainexciting field windings, is quickly reduced.

The relay 52 is also adapted to provide protection for the system in the event of relatively high main-machine voltages that are caused by the interruption of the supply circuit voltage, by reason of the trolley-pole leavin the wire, for exam le.

In t e case of a relatively lbw line voltage, the relay 52, which is connected directly across the supply circuit, drops to its lower circuit-closing position to directly connect the actuating coil 16 of the switch 16 across the terminals of the battery 78. In this way, the switch 16 is opened .to insert the resistor 61 in the circuit that shunts the exciting field winding 57 for the generator armature 55, whereby the excitation of the accelerating generator is increased sulficiently to compensate for the relatively low line voltage by insuring that a main excitin field flux is provided that is strong enoug to produce satisfactory starting conditions of the main machine. 7

The detailed action ofthe torque relay 40 in conjunction with the transformer 43, may be explained as follows:

If a part of the resistor 60 is short-circuited by the sequence drum 71, the current flowwinding 44 increases, while that in the field windlng 57 decreases, which indirectly weakens the main-machine field flux and increasesthe main current during motoring. The increase of current in the primary winding 44 increases the transformer magnetic field, thereby inducing a voltage in-the secondary winding 45 which assists in deflecting the relay armature 41 in the same direction in whic rent in the main-circuit inductive device 140. Assuming further that the relay drum 49 occupies the A position during motoring, the secondary transformer coil 47 is connected in series relation with the relay field winding 42. The increasing flux of the transformer 43 also induces a voltage in the secondary coil 47 which increases the total voltage of the field',winding 42, there by further assisting in deflecting the relay.

' If, during regeneration, a part of the resistor60 is introduced into circuit, the current in the resistor and the primary transformer winding 44 decreases, while that in the field winding 57 increases, thereby strengthening the main field flux and the regenerative current. The decrease of current in the primary winding 44 decreases the magnetic field of the transformer 43 and induces in the secondary winding 45 a voltage opposite to that mentioned above in connection with acceleration. The current in, and the voltage across, the main-circuit inductive device 140 are, however, also reit is deflected by a motoring curversed, so that the two voltages in question again add and thus cause a quick deflection of the relay, but this time in the regenerative direction. With the relay in regenerative position R, the secondary transformer coil 46 is connected in circuit/ While the voltage in the coil 46 is also reversed, its turns are connected in circuit in a reversed direction from those of the .coil 47. Thus the effect of the coil 46 during re eneration is the same as that of the coil 47 uring motoring, viz, the voltage across the relay field windlng is again increased, thereby assisting an armature and field-exciting means,

of a relay devicefer governing the automatic operation of said machine, and means for influencing said relay device by transient transformer action 1n a circuit of said exciting means.

2. In a system ofcontrol, the combination with an electric motor having an armature and a field winding, of a relay device of the motor type 'for governing the operation of said motor, and means for connecting the windings of said relay in circuit to produce a smaller time element for said relay than for the motor.

3. In a system of control, the combination with an electric motor having an armature and a field winding, of an impedance connected in the armature circuit, a resistor, and a relay device of the motor type for governing the-motor o ration and having its co-operating win ings respectively connected in circuit with said impedance and in series relationwith said reslstor and in circuitwith saidfield winding.

4. In a system ofcontrol, the combination with an electric motor having an armature and field-exciting means, of an impedance connected in the armature circuit, a plural-coil transformer having one coil connected in a circuit including said fieldexciting means, and a relay, device of the Inotortype for governing the motor operation and. having its'co-operating windings respectively connected in circuit with another transformer coil across said impedance. and connected across said field winding.

5. In a system of control, the combination with an electric motor having an armature and a field winding, of an inductive device connected in the armature circuit, a transformer having a plurality of coils, a resistor,

-.and a relay device of the motor type for governing the motor operation and having its co-operating windings respectively con-. nected through one of the transformer coils across said inductive device and connected through said resistor and another transa with a supply circuit anda'dynamo-electric former coil across saidfield windin 1 machine 6. In a system oi control,the combination with a su ply circuit and a dynamo-electric aving I an armature and a field winding, of a resistor connected "in series relation with said armature across said sup- 1 circuit, an armature for excitmg said e d winding throug'hsaid resistor, a relay device for governing the automatic operation of said machine, and means forrender in said relay device"responsive to transient v0 ta e conditions in said field winding; 1

7," n a system of control,the combination machine having an armature and a field winding, of a resistor connected in series re-' lation with said armature across said supply circuit, an armature for excitlng saidtfield winding through said resistor, a relay device for governing the automatic operation of said machine, and means for connecting the windings of said relay in circuit to roduce a smaller tune-element of response an for the windings of said motor.

- 8, Ina system of control, the combination with a dynamo-electric machine'having an armature and a field winding, of an induc- 'tive device connected in the armature circuit, an armature for exciting said field winding, afield coil for saidexciting armaa mm, a transformer havlng one coll 1n c1rcu1t one W111 n with said field coil, and a relay device for governin the machine operation and having tive' device and having another co-ogerating wlndlng connected in circuit wlbll iiferent sections of a third transforme W11'1d111g 1n accordance with the position. of'the'relay device.

9. In a system of control,the combination -with a dynamo-electric machine having any armature and a field; winding, of an induc tive device connectedginfthe",armaturecirw'- c'cuit, an armature for exciting JsaidfieId winding, afield coil'forsaid exciting arms;

tur'e, a transformer having one coil infcircuitwith said field coil, a motor-type relay device for governing the machine operation and having an armature connected in cir:

cuit with another transformer "coil across said inductive device and provided with'aj field winding havin its terminals respectively connected to t e'machine'field winding and vto an intermediate point of a third transformer winding, and a contact member actuated by the relay device for connecting the one or the other portion of said thir an armature and a field winding,

-- v corres onding to acce connected in circuit with an other trans ormer coll across saldrlnduc winding and substantial feet-fofthe fieldwinding of anot er matransformer winding in circuit with the two field windings.

10. The combination with a supply circuit and a dynamo-electric machine having of means winding, positions respectively eration and decelerationIo said machine, anda motor-type relay device havin control means effecting the connection ,0 the machine to the supply cirfor separately exciting said fie a controller having .cuit when the controlleroccupies an accelerating position and the supply circuit voltage is higher than the machine volta e, and or effecting such connection-when t e controller occupies a decelerating position and the supply-circuit voltage is lower than the machine voltage.

,11'; The combination with a sup ly circuit and a dynamo-electric machine aving an armatureand a field winding, of a switch for connecting the machine to the supply circuit, ajrelay device for governing certain gmotor connections and having its co- 'dynamo-electrlc machines severally having armatures and field windings, of means for separately exciting said field windin s, and means forefi'ecting transition of t e mach nesffrom series to. parallel relation comprising means for impressing a relatively high exciting volta e upon one field windmg and'substantia y nullifying, the effect of the field winding 3 of another machine,

means for closing a local circuit around that" machine, means for connectin the field wlndlngs 1n local-parallel relatlon, and means forconnectlng the 'armatures in parallel relation across thesupply circuit.

13. The method of eflecting transition of a "plurality of separately excited dynamoelectric machines'from series to parallel relation, which consistsin impressing an increased exciting Yvoltage upon one field y, nu

chine, closing a local circuit around that machinaand connecting the field windings and then the armatures in parallelrelation.

. 14. The method of effecting series-parallel lifyin the ct transition of a plurality of separately excited motors which consists in substantially nullifying the effect of the field winding of "one machine, closing a local resistance cir- 1 cult around that machine, connecting the field windings in local parallel relation, and connecting the armatures in parallel relation.

15. The method of effecting transition of a plurality of separately excited dynamoelectric machines from series to parallel relation which consists in impressing an increased exciting voltage upon one field winding and substantially nullifying the effect of the field winding of another machine, further strengthening the exciting voltage, closing a local resistance circuit around the last-named machine, reducing the exciting voltage, connecting the field windings in local parallel relation and connecting the arlnatures in parallel operating relation.

16. In a system of control, the combination with a dynamo-electric machine having field-exciting means, of means for governing the operation of said machine, and means for influencing said governing means citing said field winding through said device, means for governing the o ration of said machine, and means for ren ermg sald governing means responsive to transient electrlcal conditions in said field windlng.

In testimony whereof, I have hereunto subscribed my name th1s'24th day of April, 1919.

RUDOLF E. HELLMUND. 

